TEXT-BOOK OF BACTERIOLOGY. 267 



shall first elaborate it by procedure on the plate. If during the 

 first twenty-four hours colonies should develop whose nature is in 

 doubt, but may be comma bacilli, it will suffice to transport one of 

 them to bouillon containing peptone and place this in the incubator. 

 After twelve hours a definite conclusion may be reached 'by the aid 

 of sulphuric acid. 



This method is more effective when applied in connection with a 

 procedure introduced by Gruber .and Schottelius. These two in- 

 vestigators availed themselves of the fact already naentioned. that 

 the cholera bacilli thrive particularly well in strongly-diluted bouil- 

 lon. The predilection of the cholera vibriones for this medium is 

 so pronounced that they remain victorious on it even in competition 

 with other micro-organisms, and flourish specially luxuriantly on 

 the surface of the fluid, as may be recognized by the well-known 

 wrinkled film. In the examination of any material, especially the 

 intestinal contents of a corpse or the discharges of a patient, for 

 cholera bacteria, we prepare gelatin plates of it, and at the same 

 time inoculate a number of test-tubes filled with a strongly-diluted 

 food bouillon; then place them in the incubator and examine them 

 in twelve to twenty-four hours. If there has been formed anywhere 

 a film, we must examine it carefully. If it appears suspicious, pre- 

 pare plates from it and transmit a trace of it to a new tube with 

 diluted bouillon; especially endeavor to ascertain by means of spe- 

 cific reaction whether there are any cholera vibrios present. If 

 the result be affirmative, diagnosis will have been established after 

 twelve to twenty-four hours ; but if negative, we must watch the 

 development. In those cases where there were but very few comma 

 bacilli from the beginning, the examination must be conducted with 

 the greatest care by the use of the plate. 



This exhausts our knowledge concerning the comma bacilli and 

 their mode of life; but the aim has been to present evidence suffi- 

 cient to establish the fact that in them we have a definite, well- 

 circumscribed, and, above all, an easily-recognized and distinguish- 

 able kind of bacterium. 



It was demonstrated by Koch in all cases of cholera asiatica, 

 usually in the intestines in great abundance and even in a state 

 approaching pure cultures. This fact has been verified by a.ll con- 

 scientious investigators, and no case of genuine cholera has as yet 

 been reported in which the comma bacilli have been absent. 



Koch has shown, furthermore, that their occurrence is abso- 

 lutely restricted to cholera; that thej' appear in no other affection; 

 that they appear with the outbreak of the disease and disappear 

 with its cessation. This observation, too, has proved correct in 



